It’s May 7th, and May 7th is Jupiter Day, because Jupiter Day is May 7th. It says so right here.
Let’s talk Jupiter.
The Name
Jupiter is named after Jupiter, the Romans’ greatest god. This is like if we worshipped cookies and named a planet Chocolate Chip. Is it everyone’s favorite? No. But it’s some people’s favorite, and it’s the greatest.
The Story
Humans have known of at least the light Jupiter reflects for more than 2,700 years. The Babylonians looked at Jupiter. The ancient Chinese looked at Jupiter and built the Chinese zodiac around what we ultimately learned was Jupiter’s rotation around the Sun. Galileo realized Jupiter had moons in 1610, which was a big deal because it backed up Copernicus’s (and Aristarchus of Samos’s) assertion that basically said, “Planets exist, Earth is one of them, and we all rotate around the Sun.”
Jupiter itself, of course, has existed for much longer than 2,700 years. At least three thousand for Jupiter! Really, Jupiter is probably 4.6 billion years old and is probably the oldest planet in the Solar System. Estimates of Jupiter’s age put it at around 50 million years older than our wet little rock, a comparable magnitude of time to how long it’s been right now since we had dinosaurs around.
The Size
Jupiter’s defining characteristic is its size. It’s really big. It’s really, really big. It’s so big that you could lump all the other planets in our solar system together and they’d still only weigh about 40% as much as Jupiter weighs. Why is Jupiter so big? It sounds like it ate other planets. That isn’t the whole story—if I had to guess, I’d guess it was the biggest planet on the block and other planets got too close and got swallowed alive, in a circular trend—but it seems to be part of it.
Weight isn’t the only weigh (*giggle*) to measure size, and Jupiter’s volume is also gigantic. It’s as big as some of the smallest stars. When the Milky Way crashes into whatever galaxy it’s supposed to crash into, Jupiter is our best local fighter besides the Sun. Probably won’t help matters, but we are going to look to Jupiter for help anyway. Jupiter, please start preparing. We need you.
The Gas
Jupiter is famously gassy, but it’s also liquid, and it’s about as dense as simple syrup. But don’t try to drink it, am I right!!! You would fail. None of you could drink Jupiter. No matter how hard you tried. You can do a lot of things with your life, but drinking Jupiter is not one of them.
What gas is Jupiter? It sounds like it’s mostly hydrogen and helium. This is why Jupiter looks so much like a balloon.
The Storms
Jupiter is cloudy, but its clouds move pretty slowly relative to ours. This gif is one Earth month’s worth of cloud movement on Jupiter. The clouds do look cool. They have a bunch of bands and lines, which makes Jupiter resemble an ice cream flavor I can’t quite place. They also don’t change very often. We’ve known about the Great Red Spot for over 350 years. Jupiter weather, guys. You know? Always the same. It’s like San Diego, except inhospitable to human life.
The Rings
Jupiter does have rings, but they don’t get as much love as other planets’ rings, probably because they’re small. They’re not *that* small, of course—it’s Jupiter, everything is huge—but they aren’t as noteworthy as Saturn’s or Uranus’s. This might tie back into how convincingly Jupiter won all its collisions with other planets and other space rocks. Uranus took a beating in its big fight.
The Moons
Jupiter’s moons are a big deal. Ganymede is the biggest, and it’s bigger than even Mercury, but Jupiter has at least 95 moons. This is an absurd number of moons. The four biggest—Ganymede and its friends Io, Europa, and Callisto—are the main story, though. Together, they contribute 99.997% of the moons’ collective weight. So, I don’t know, I feel like we’re on our way to saying Jupiter has four moons and then finding another term for the little moons. If astronomers had enough time on their hands to reclassify Pluto, they will one day get around to making a new term for tiny little insignificant rinky-dink moons.
The Human Touch
Humanity has sent eight robots to Jupiter, and we’ve got another on its way. One of these—Galileo—crash-landed into Jupiter. This was intentional—Europa might have life, so scientists wanted to get Galileo taken care of and eliminate any chance Galileo messed up Europa’s life—but it was still a pretty dramatic move. The thing disintegrated as it entered the atmosphere.
The Sky (Our Sky, Specifically)
Jupiter’s a big deal in the sky. It’s the fourth-brightest light we get from outside our planet, trailing the Sun, the Moon, and Venus. Tonight, on Jupiter Day 2023, looking from the middle of the United States, it sounds like Jupiter’s going to be below the horizon, if I’m reading The Internet correctly. Tomorrow morning, though, it looks like it’ll rise around dawn, depending where in America you are? I’m not used to this, guys. Use the Star Chart app. That thing’s great and free. I would look myself but I am on an airplane right now. Nowhere near Jupiter. Airplanes are not meaningfully closer to Jupiter than people are when they are on the ground.
One big thing Jupiter’s up to this month is crashing into the Moon. Our Moon. Not literally, but the Moon’s going to block Jupiter on the morning of May 17th. Kind of fun.
How to Celebrate Jupiter Day
I mean, you’re probably teaching your kid about Jupiter as a fun activity. Hard to believe anyone’s doing more than that today. That’s why I left the cuss words out. I was going to say much meaner things about Jupiter’s 91 known lesser moons. So you better tell your kids. I’m talking to you, Pat. I heard how many questions Blake was asking yesterday. Please tell him about Jupiter Day for me.
